Fix zmq_ctx_get_ext not setting the length of the out string
#1289
| Job | Run time |
|---|---|
| 5m 22s | |
| 0s | |
| 2m 36s | |
| 2m 40s | |
| 3m 36s | |
| 3m 24s | |
| 8m 15s | |
| 3m 28s | |
| 3m 27s | |
| 15s | |
| 2m 58s | |
| 3m 5s | |
| 2m 52s | |
| 2m 57s | |
| 3m 35s | |
| 3m 12s | |
| 4m 0s | |
| 55m 42s |